Tech Question: Different Tyre Selection on Front and Rear

[projectdstage5]

I have been reading up on this via various sites. Some sites say it is okay, as long as (1) the front two are tyre type A and the rear two are tyre type B and (2) the new tyres are fitted to the rear. E.g. Celtic Tyres::Tyre Tips - New tyres to the rear.

Other forums say it will drastically affect handling characteristics and is downright dangerous when the car is used in performance driving situations.

Some time attack cars, drag cars also use different set ups. E.g. semi slick fronts and Hoosier rears.

Can the scientifically inclined / track specialists feedback your views on this?

The reason for this question is that my Michelin Pilot Sport Cups are worn to the thread in the front, but the rear tyres are very good and have minimal wear. It is rather wasteful to change all four tyres. I was thinking of changing the worn slicks to Pirellis. This means the setup is front (used Michelins) and rear (new Pirellis). I don't think tread pattern should factor, because semi-slicks barely have any tread anyway. How is this going to handle on the track?

Note: My rims are the same size all round, no staggered set up. Of course the no brainer answer is to just use back the same brand of tyres. But if there is no stock left and i can't wait 3 months to indent, I have to consider alternatives.

Cheers

 

[Shaun]

Re: Tech Question: Different Tyre Selection on Front and Rear

It's not dangerous at all running different tires F and R. You just need to inch up on the limit starting with low speed turns explored fully before moving to mid speed ones and ending with high speed turns. Just don't run corded tires (near zero grip / split risk), slicks in heavy rain (aquaplane), etc.

It's not ideal and the balance will change in the direction of loose, but not drastically so to where it's too loose if the base setup was pretty tight - which the tire wear you describe hints at. But it's only one of a few factors so it's not for sure, just an indication.

In general, there is upside to tracking the car with new balance in that you learn how to drive around the inefficiencies. Cars are never perfect and the more committed to adapting the driver is, the better he'll be in the end, and in future cars too. It's another reason not to to keep throwing parts at cars and tweaking setups to fix "problems" despite being miles off on the driving basics and having no measurements - only feel to go by. The mind is too easily tricked.